1. Technical Field
The present invention relates to a Power Distribution Unit (PDU) that can detect system status. In particular, the invention relates to a PDU in which a I2C device driving power source is disposed therein, and which can turn AC power on and off by remotely monitoring system power as needed except when AC power fails.
2. Related Art
The earlier PDU shared system power and I2C power or used power supply units which were disposed exterior of the PDU for the I2C power. That is, it did not use power which was directly supplied from the PDU.
The earlier PDU uses a line filter, a power sensor which monitors the status of system power in accordance with a I2C device, and a relay and on/off switch circuit which turns the system power on and off in response to the I2C device through a I2C BUS.
The line filter filters AC supplied to said PDU and supplies AC to system power and the I2C device through a power sensor disposed within the PDU and the relay and on/off switch circuit.
The power sensor senses the power status of the system and transfers the power status information to the I2C device through the I2C BUS.
The relay and on/off switch circuit turns system power on and off by switching on/off according to system power information monitored by a management unit, which is delivered through the I2C BUS by the I2C device.
However, since the I2C device is driven by the same power source that is supplied to said system power, it cannot be turned on/off separately from the system power. Therefore, when DC power or system power fails, the system management unit with the system status information also shuts down. Consequently, when DC power or system power fails, problems in system status cannot be monitored via the I2C device. As well, the stability of the I2C power was low because directly supplied power from the PDU was not used, and it was not possible to remotely turn system power on and off in an emergency.
The patent to Saadeh et al., U.S. Pat. No. 5,283,905, entitled Power Supply For Computer System Manager, discloses a power supply arrangement in which the power supply has its own secondary power source operable when input power to a computer system manager no longer meets preset threshold values.
The patent to Kikinis, U.S. Pat. No. 5,579,524, entitled Optimized Power Supply System For Computer Equipment, discloses a power supply system for a general purpose computer which has plural power supplies for powering selected groups of components. One of the power supplies serves the keyboard and its controller and the keyboard controller is configured to turn the other power supplies on and off in response to user input at the keyboard.
The patent to Ugajin, U.S. Pat. No. 5,652,892, entitled Method And Apparatus For Controlling Remote Power Source, discloses a remote power source control for a system having a plurality of information processing apparatus interconnected by a network or network capable of controlling remote power sources. Each information processing apparatus is provided with a remote power source controller which is always operated by an auxiliary power source.
The following additional patents each disclose features in common with the present invention but are not as pertinent as the patents discussed in detail above: U.S. Pat. No. 5,481,730 to Brown et al., entitled Monitoring And Control Of Power Supply Functions Using A Microcontroller, U.S. Pat. No. 5,596,758 to Yatsuzuka, entitled Memory Protecting Device For Use In Compact Electronic Apparatus Equipped With An External Power Supply, U.S. Pat. No. 4,677,566 to Whittaker et al., entitled Power Control Network For Multiple Digital Modules, U.S. Pat. No. 5,511,205 to Kannan et al., entitled System For Distributed Power Management In Portable Computers, and U.S. Pat. No. 5,652,891 to Kitamura et al., entitled Computer Apparatus And External Storage Device Which Can Be Used By External Power And Internal Power Source.
While each of the aforecited patents discloses features in common with the present invention, none of them teaches or suggests a power distribution unit that can detect system status in accordance with the present invention.